Minimum multiple of m where digital sum equals m
Generate the sequence a(n) when each n is the minimum integer multiple m such that the digit sum of n times m is equal to n.
Minimum multiple of m where digital sum equals m is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
- Task
- Find the first 40 elements of the sequence.
- Stretch
- Find the next 30 elements of the sequence.
- See also
- [oeis:A131382|OEIS:A131382 - Minimal number m such that Sum_digits(n*m)=n]
Raku
<lang perl6>sub min-mult-dsum ($n) { (1..∞).first: (* × $n).comb.sum == $n }
say .fmt("%2d: ") ~ .&min-mult-dsum for flat 1..40, 41..70;</lang>
- Output:
1: 1 2: 1 3: 1 4: 1 5: 1 6: 1 7: 1 8: 1 9: 1 10: 19 11: 19 12: 4 13: 19 14: 19 15: 13 16: 28 17: 28 18: 11 19: 46 20: 199 21: 19 22: 109 23: 73 24: 37 25: 199 26: 73 27: 37 28: 271 29: 172 30: 1333 31: 289 32: 559 33: 1303 34: 847 35: 1657 36: 833 37: 1027 38: 1576 39: 1282 40: 17497 41: 4339 42: 2119 43: 2323 44: 10909 45: 11111 46: 12826 47: 14617 48: 14581 49: 16102 50: 199999 51: 17449 52: 38269 53: 56413 54: 37037 55: 1108909 56: 142498 57: 103507 58: 154981 59: 150661 60: 1333333 61: 163918 62: 322579 63: 315873 64: 937342 65: 1076923 66: 1030303 67: 880597 68: 1469116 69: 1157971 70: 12842857